This video documents the complete process of constructing, firing, and operating a pair of clay water bellows using primitive technology. The project begins with the fabrication of two bellows from uniform clay slabs, assembled using a staggered-layer technique for strength. A temporary kiln is constructed from dry-stacked bricks, and additional bricks are made from recycled clay to act as thermal mass for a controlled firing. The video details a multi-day firing process, including a slow initial drying phase to prevent cracking and a three-hour high-temperature firing. Post-firing, the bellows are completed with leaf flap valves. The final setup involves digging a clay-lined (puddled) pit to hold water and crafting a special double-spout tuyere to combine the airflow from both units, successfully demonstrating their use in intensifying a fire within a brick furnace.
Building and Firing Clay Water Bellows
00:00:11 Building with Clay Slabs: The project begins by creating consistent, uniform clay slabs using a cane frame as a guide. The bellows are built upside down, starting with a 25 cm disc for the top.
00:02:50 Staggered Slab Technique: To ensure structural strength, the clay slabs are layered in a staggered pattern over the joints of the layer below. The final bellows measure 25 cm tall, 25 cm wide, and 50 cm long.
00:04:11 Temporary Brick Kiln: A kiln is built by dry-stacking bricks. New bricks are also made from recycled furnace clay to add thermal mass, which ensures the bellows are fired slowly without sharp temperature changes that could cause cracks.
00:08:25 Multi-Stage Firing Process: The firing is a careful, multi-day process. First, a low fire is maintained for a full day to slowly and completely dry the still-damp pottery. The next day, the main firing begins, stoking the kiln for 3 hours until the bellows glow orange-hot.
00:10:44 Leaf Flap Valve: After the firing is complete, an effective flap valve is created for each bellows using a folded leaf, which is attached over the inlet hole with bark fiber string.
00:12:32 Ash for Mortar: A useful byproduct of the firing process, wood ash, is collected, sifted, and mixed with water to create pellets that can be used as an ingredient for brick mortar in future projects.
00:13:54 Clay Puddling: To create a waterproof pit for the bellows to operate in, the pit is dug in sandy soil and then lined with a thick layer of clay to prevent water from soaking away.
00:15:33 Operating Rhythm: A key takeaway is that when using two bellows in the same puddle of water, a rhythm must be established to prevent the waves created by one from canceling out the motion of the other.
00:15:50 Custom Double Tuyere: A special Y-shaped clay tuyere is crafted and dried by the fire to combine the airflow from both bellows into a single, more powerful air blast.
00:17:07 Improved Handle: After an integrated clay handle breaks off, it is replaced with a lashed-on wooden handle, which provides a better and more comfortable grip.
00:18:21 Successful Operation: The completed system, featuring two bellows connected to the double tuyere, is shown successfully shooting a powerful blast of air directly into the coal bed of a brick furnace, demonstrating the project's success.